The present invention relates to a novel low-calorie chocolate and to a process for manufacturing the said chocolate.
Three types of chocolate can be distinguished: dark chocolate, milk chocolate and white chocolate.
Generally, traditional dark chocolate may be defined as a product which is obtained from cocoa paste consisting of a cocoa liquor containing about 54% of fatty substances, sucrose and cocoa butter. Milk chocolate contains milk in addition to the dry matter. White chocolate also contains milk but lacks desiccated defatted cocoa.
All these chocolates may contain filling ingredients such as hazel nuts, crisped rice, desiccated fruits or the like.
From a physical point of view, a chocolate may be assimilated with a practically anhydrous dispersion of very fine nonfatty particles (sucrose, lactose, proteins, minerals and the like) in a solidified fatty phase consisting essentially of triglycerides. The latter are solely derived from cocoa in the case of a dark chocolate, but are derived from milk in the case of milk or white chocolate.
A conventional process for the manufacture of chocolate comprises the following successive essential stages: kneading--refining--optionally dry conching--liquid conching--tempering--moulding--cooling--packaging.
Kneading is intended to produce a homogeneous paste from sugar, cocoa paste and optionally from cocoa butter and milk powder. The operation is carried out in a mechanical kneading machine. The paste obtained should have a specific texture, which is appropriate for the subsequent refining operation. It is possible to control the texture by the choice of the particle size of the sugar and also by the fat content.
Refining consists in rolling the paste obtained from the kneading, between steel rollers so as to reduce the size of the particles to less than 25 microns. This operation transforms the initial paste into a fine powder which is hygroscopic and capable of trapping ambient odours. At this stage, it is therefore desirable for conching to take place as rapidly as possible.
Conching is essential for modifying the flavour and improving the rheological characteristics of the chocolate. This operation can be carried out in a single stage (liquid conching) or in two stages (dry and then liquid conching) and may last from a few hours to several days. The refined powder is worked at high temperature, at around 75.degree.-80.degree. C. in the case of a dark chocolate, and at around 65.degree. C. for white and milk chocolates. Dry conching consists in performing this high temperature working in the absence of high fat contents. It enables the conching time to be reduced.
The chocolate flavour is developed during this operation. By virtue of the temperature increase and the aeration of the mass used, undesirable compounds such as aldehydes and short-chain fatty acids escape from the mass by volatilisation while other flavouring compounds are formed. Furthermore, the rheology of the product changes: the powder obtained at the end of the refining progresses towards the pasty state. The insoluble particles (of sugar, cocoa, milk and the like) are dissociated by friction and separation of water and become rounded so as to communicate greater flowability to the paste, with a lower yield point. To further improve these characteristics, lecithin is added to the chocolate a few hours before the end of conching. The lecithin coats the sugar particles and emulsifies the residual traces of water to give the chocolate good flow properties which are essential for the subsequent moulding stage.
Tempering of the chocolate is intended to permit crystallisation of the cocoa butter in stable form. For that, the chocolate paste is adjusted to a temperature of about 29.degree. C., sometimes slightly less, so as to create seed crystals of all sorts, and then to a slightly higher temperature during the moulding, so as to melt the unstable crystalline forms.
Moulding is an operation for shaping chocolate, for example, into tablets or into figurines. The chocolates may be solid or filled. So-called "couverture" chocolate, which is intended for coating the surface of products such as cakes, cereal bars, candied fruits and the like, also exists.
During the cooling stage, the fatty substance congeals by crystallisation into a stable form if the tempering operation was well conducted. In the opposite case, the chocolate may be difficult to remove from moulds, may melt between the fingers and may also deteriorate over time due to a phenomenon called fat bloom.
Other production techniques are sometimes used. The one best known is the "crumb" technique which is widely used in England for the production of milk chocolates. It consists in mixing milk or concentrated milk products containing 30-40% dry matter with sugar, in heating the mixture to boiling point under vacuum at about 75.degree. C. and in working this mixture with cocoa paste before drying under high vacuum in order to obtain a powder containing less than 1% water. This process makes it possible to obtain a milk chocolate having organoleptic properties which are very different from those obtained with the conventional method.
Sucrose has been the reference sweetening mass since the beginning of the chocolate industry. Its organoleptic and technological properties render it particularly suitable for this type of confectionery product.
On the other hand, its nutritional properties may be open to criticism. Indeed, sucrose has a calorific value of 4 kcal/g, which gives to the chocolate, of which sucrose is the essential constituent, a high calorific value.
Moreover, it is known that sugar is completely contraindicated for diabetics because the glucose constituting it can be rapidly assimilated by the organism, which may generate severe hyperglycemia in these patients.
Finally, sucrose is a substrate which can be fermented by the commensal bacteria in the mouth, which convert it to corrosive acids which are responsible for tooth decay.
To overcome these disadvantages, the idea was developed to substitute polyols for sucrose in chocolate. These polyols may be in particular hydrogenated monosaccharides such as sorbitol, mannitol, xylitol, erythritol or hydrogenated disaccharides such as maltitol, lactitol, hydrogenated isomaltulose (equimolar mixture of 1,6-glucopyranosylsorbitol and 1,6-glucopyranosylmannitol).
In the pure state, these polyols have no reducing power and are not fermented into acids by the flora of the buccal cavity. They therefore permit the manufacture of noncariogenic chocolates insofar as the other ingredients of the formulation do not provide fermentable sugars. In the case of milk chocolates and white chocolates, the milk may be replaced by lactose-free milk ingredients so as to best ensure this hypocariogenicity.
Polyols are slowly metabolised and they do not cause a sharp rise in the level of blood glucose following their consumption. Consequently, they are often recommended in the diet for diabetics.
Furthermore, their calorific value is estimated at a mean value of 2.4 kcal/g (10.0 KJ/g), that is to say about 60% of that for sugar.
However, as far as calorie reduction is concerned, it can only be observed that it still remains limited in the case of the polyol-containing chocolates currently available, this being for the simple reason that in addition to the calorific value of the sweetening mass, there is the substantially greater calorific value of fatty substances which constitute another essential ingredient of the chocolate.
These fatty substances are in the form of triglycerides and are generally obtained from cocoa and/or milk. They differ from other fatty substances in their capacity to be metabolised, at least partially, without causing gastrointestinal disorders or without even affecting the metabolism of vitamins.
Their calorific value indeed amounts to 9 kcal/g. Furthermore, they are essentially in a saturated form. They are not therefore particularly recommended by nutritionists and are against the current concern of consumers to limit the excessive supply of calories by diet.
To respond to this concern, it would therefore be appropriate, in the case of chocolate, to replace sucrose with a low-calorie substitute, polyols being especially quite suitable for this purpose, but also to reduce the amount of fatty substances. However, there are technological manufacturing imperatives including in particular the rheological properties which are necessary in order to perform the refining, conching and moulding operations under satisfactory conditions, which a priori prevent a substantial reduction in the fat content in polyol-containing chocolates.
This is true particularly for refining, which is a stage in which the paste must be sufficiently cohesive in order to be properly suitable for grinding in the rollers of the refining device. A paste which is too dry would render the rolling impossible. Furthermore, the fatty substances are essential in order to impart malleability to the paste, which permits good refining. At this stage of the manufacture, it seemed, until now, impossible to have a fat content of less than 28% for polyol-containing chocolate. Such a threshold would deprive the manufacturer of the advantageous opportunity of applying dry conching which promotes the separation of water.
These fatty substances are also very important during conching and moulding because they impart the appropriate rheology to the paste and temper the effects of the polyols which, by virtue of their hygroscopicity, rather tend to increase this viscosity as will be seen below. It should be noted that the addition of an emulsifier such as lecithin, which is prior to conching and which is intended to reduce the viscosity of the chocolate paste, can compensate the reduction in the fat content only to a certain degree. Indeed, an excess of lecithin would lead to the formation of too stable a water-in-oil emulsion which would prevent the evaporation of water and volatile compounds which is sought during conching, and, worse still, may also lead to an effect which is the reverse of that sought, namely an increase in the yield point of the chocolate paste.
There is another difficulty to be overcome when attempts are made to reduce the fat content of a chocolate. Indeed, one of the roles of the fatty substance in chocolate is to form a continuous and solid cross-linkage between the cocoa particles and the particles of sweetening agent. It constitutes, in a way, a cement which ensures the cohesion, the consistency and the hardness of the chocolate after cooling. It should therefore be ensured that these properties are not affected.
Finally, the greater the reduction in fatty substances, the more difficult it is for the fatty phase to crystallise in a stable crystalline state, that is to say one which enables the chocolate not to progress towards a matt and whitish appearance which is typical of the phenomenon known as fat bloom and which is quite damaging to the product.
It therefore appeared impossible, until now, to manufacture polyol-containing chocolates containing less than 32%, preferably less than 31%, and still more preferably less than 29% of fatty substances.
Moreover, as already mentioned, some polyols may be constraining with respect to the chocolate manufacturing process especially because of their high hygroscopicity which poses problems as regards storage and during the implementation of the process. It is thus recommended to provide for the use of conditioned atmospheres with controlled humidity levels in order to avoid water being taken up. This phenomenon is observed for sorbitol in particular.
Still with respect to these hygroscopicity problems, the brittleness and the morphology of the crystalline powders of some polyols, such as sorbitol and hydrogenated isomaltulose, cause, during refining, the formation of particles having a specific surface area which is greater than that of sugar. This renders the worked paste more hygroscopic and therefore more viscous, and requires the use of a higher amount of fatty substances in order to improve the rheological behaviour of this paste.
Moreover, the temperature increases which occur directly or indirectly during the grinding, kneading, refining, or conching operations render the polyols more unstable.
Firstly, their hygroscopicity increases. In the specific case of sorbitol, the critical relative humidity which should not be exceeded in the manufacturing environment, thereby drops from 73% to 62% when the temperature is increased from 20.degree. to 40.degree. C.
Secondly, the temperature increases may result in a disorganisation of the crystalline states, by releasing the water of crystallisation when the relative humidity is low for the polyols of hydrated crystalline form (hydrogenated isomaltulose, lactitol monohydrate and the like), or by melting of the crystals for the polyols having a low melting point (xylitol, sorbitol and the like), this melting of the crystals corresponding to their transition to a very hygroscopic amorphous state.
It was therefore necessary to limit the conching temperature for example to 40.degree.-48.degree. C. for sorbitol and to 65.degree. C. for lactitol monohydrate, all the more so since the phenomenon of water regain increases per se much more substantially at high temperature than at low temperature given that polyols are thereby more soluble and therefore pass more rapidly and more easily from the crystalline state to the hygroscopic amorphous state, thus intensifying the regain of water.
However, it should be noted that the regain of water during conching leads to thickening or even to agglomeration of the worked paste. Moulding therefore becomes very difficult or impossible and, in any case, the finished product is of poor quality. For example, it has a grainy and sandy texture.
This conching temperature limitation reduces the effects of this stage which is essential for developing the chocolate flavour and for improving its rheological qualities. And increasing the conching time, which is economically damaging to the manufacturer, does not really enable this disadvantage to be overcome: the removal of water and bitter volatile compounds by evaporation is inadequate.
The only remaining solution therefore is to use raw materials lacking water and more highly processed, and therefore more expensive.
To illustrate this inability of chocolate manufacturers to bring under control the reduction of the fat content of polyol-containing chocolates, as well as the technological problems affecting manufacture which are linked to the physicochemical properties of these ingredients, there may be mentioned for example Patent FR 2,201,042 which, in Example 18, p. 20 of the description, discloses the preparation of a sucrose- and lactitol-containing chocolate containing not less than 32% by weight of fatty substances, and this is a threshold below which it is impossible to manufacture chocolate. But it still represents a relatively high amount and this is all the more so since the sweetening mass essentially consists of sucrose which is a high-calorie and cariogenic product.
Similarly, Patent FR 2,499,576 relating to anhydrous maltitol crystals, teaches, in Example 10 thereof, the application of the said crystallised maltitol in the manufacture of sugar-free chocolate, but this chocolate still contains 32% by weight of fatty substances.
European Patent Application No. 0317917, for its part, relates to a process for manufacturing sugar-free and noncariogenic milk chocolate using the so-called "crumb" technique. The sugar substitutes used in this process are maltitol, lactitol or hydrogenated isomaltulose (equimolar mixture of 1,6-glucopyranosylmannitol and 1,6-glucopyranosylsorbitol, which is marketed under the registered trade mark ISOMALT). The chocolates manufactured according to this process have a fat content which is not less than 35% by weight. It should also be noted that the "crumb" technique is quite special and differs substantially from traditional techniques for manufacturing chocolate.
The technical presumption that it was a priori technically impossible to reduce the fat content of polyol-containing chocolate, of maltitol-containing chocolate in particular, below 32% by weight, is clearly evident from Japanese Patent Application No. 60/232058 which describes a chocolate in which sugar is replaced with a mixture of maltitol powder and lactose or maltose or mannitol or a mixture of these. The fat content of some of the chocolates, whose preparation is described in the examples and in the control tests, is of the order of 26.5% by weight, but it is explicitly indicated in this patent application that the chocolate, whose sweetening mass consists solely of maltitol (control 2), is of poor quality, namely that it is granular, that it has a sweet taste which is unsatisfactory and that it has a sandy feel on the tongue. Furthermore, it is also stressed that its production process is very difficult to implement. The polyol used consists of a maltitol syrup powder. This maltitol-containing chocolate is used, moreover, as negative control which is intended to demonstrate the advantages of the invention which is claimed in this application and which, precisely, provides for the use of the mixture of maltitol and at least one other sugar such as maltose, lactose or mannitol, in order to overcome the disadvantages of a low-fat chocolate whose sweetening mass would consist solely of a polyol such as maltitol. The reading of this document could only therefore have convinced a person skilled in the art not to use maltitol as sweetening mass for preparing a low-fat polyol-containing chocolate.
With respect to maltitol and this problem of reducing the fat content of foodstuffs, European Patent Application No. 390,299 should also be mentioned, which relates to an improved, fat-containing foodstuff in which the improvement consists in the complete or partial replacement of the fat by an amount of maltitol which is effective tastewise. On the one hand, the trivial nature of this invention will not pass unnoticed, knowing, in particular, that maltitol has been known as a sugar substitute for quite some time, and neither, on the other hand, will the fact that the chocolate is not explicitly mentioned among the products which are the target of this invention. Consequently, the problems which are specific to the processes for manufacturing chocolate, such as for example the regain of water and the rheological behaviour which have been mentioned above, are absolutely not addressed. Yet, as has been seen, these specific problems are such that they can greatly hamper the reduction of fatty substances in chocolate.
Moreover, only the complete substitution of maltitol for fatty substances is addressed in this patent application. Yet, it is not inconceivable that the reduction of fatty substances in fatty and sugary foodstuffs such as chocolate, could be compensated for by an increase in the amount of desiccated defatted cocoa. The content of this patent application is not to be taken into account within the context of reducing the fat content of chocolate. And this may furthermore be confirmed by a technical publication, dated Jan. 6, 1990, from the patentee of this European patent application, the company TOWA CHEMICAL INDUSTRY Co., relating to maltitol powder which is marketed by it under the registered trade mark AMALTY.
This publication indeed contains, page 4, an example of application of AMALTY to the preparation of chocolate. The no. 1 handling precaution which is mentioned therein stipulates that the amount of cocoa butter should be slightly increased given that AMALTY absorbs more fat than does sugar because of its greater porosity. Moreover, it is evident that the fat content in the maltitol-containing milk chocolate formulation proposed is about 38.4% by weight.
Therefore, nothing in this document indicates or even suggests that a polyol such as maltitol is suitable for manufacturing chocolate with a reduced fat content.
Another article, which appeared in CONFECTIONERY MANUFACTURE & MARKETING Vol. 22, No. 5 of MAY 1985, mentions the application of maltitol powder which is marketed under the trade mark MALBIT by the company MELIDA, in the preparation of chocolate with a reduced fat content. It is again evident that this reduction is limited to 36-37% by weight for milk chocolate.
With respect to another polyol which is used as sweetening mass in sugar-free chocolate, namely lactitol monohydrate, Patent Application WO 90/06317 teaches that the fat content achieved for dark chocolate and milk chocolate, prepared using the said polyol (Examples 4 and 5), is 33% and 32.5% by weight respectively.
This technological deficiency may be extended to many polyols other than those mentioned above. And this is supported by the article by Anne CRIDLAND entitled "Developments in dietetic chocolate" which appeared in Volume 24, No. 10, of 1987, pp. 2 to 6 of the journal CONFECTIONERY MANUFACTURE & MARKETING, in which the author explains, page 6, in the paragraph entitled "Fat", that the fat in chocolate is probably the most important element with regard to the technical and textural properties of the product and that there is in existence no chocolate with a reduced calorific value and with a pleasant taste, which satisfies the required technical functions.
Acknowledging this state of the art, the applicant company set itself the objective of developing a low-calorie chocolate which, although having a very reduced fat content, being less than 32%, preferably less than 31% and still more preferably less than 29% by weight, would have technological and organoleptic properties comparable to those of traditional sucrose containing chocolate.
Comparable technological properties are understood to mean both the properties of the chocolate obtained and the possibility of having recourse to a conventional technology for its manufacture, and using, up to the conching stage, the same ingredients as for a conventional chocolate, except for the sweetening mass. The desired aim is in fact to dispense, as far as possible, with, on the one hand, operational constraints such as a conditioned atmosphere, a sophisticated equipment or a long manufacturing time, and, on the other hand, technical difficulties such as the regain of water, poor rheological behaviour or limitation of the conching temperature.
And it was after numerous tests and studies that the applicant company took the credit for finding that the above-defined objective could be achieved provided that products selected from the group consisting of crystallised maltitol of high purity, lactitol, hydrogenated isomaltulose or low-calorie saccharide polymers or a mixture thereof, are used for constituting the sweetening mass.